Problem: $ { {-5} \times \left[\begin{array}{rrr}{-1} & {-1} & {3} \\ {0} & {0} & {0}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{-5}\times{-1} & {-5}\times{-1} & {-5}\times{3} \\ {-5}\times{0} & {-5}\times{0} & {-5}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{5} & {5} & {-15} \\ {0} & {0} & {0}\end{array}\right]}$